Throughout the climate swings of the Pleistocene, the ice sheet that covered North America—one larger even than modern Antarctica—did not merely shrink in response to a few degrees of warming, writes Peter Brannen in Ends of the World, it exploded: “Rather than slowly dwindling over thousands of years, these continents of ice sometimes violently disintegrated in spectacles that unfolded over mere centuries. In one rapid collapse 14,000 years ago, called Meltwater Pulse 1A, three Greenlands’ worth of ice fell into the sea in icy flotillas, sending sea level soaring 60 feet.”

During this explosive epoch of change, modern humans were evolving in China. Excavations in Middle Pleistocene cave deposits in southeastern China have yielded a largely complete skull that exhibits similarities to other East Asian Middle and Late Pleistocene human remains, but also foreshadows later modern human forms.

Fossil evidence for human evolution in East Asia during the Pleistocene is often fragmentary and scattered, which makes evaluating the pattern of archaic human evolution and modern human emergence in the region complicated.

A team of scientists led by Liu Wu and Wu Xiujie with the Chinese Academy of Sciences reported the first ever Middle Pleistocene human skull found in southeastern China, revealing the variation and continuity in early Asian humans.

Wu Xiujie and his colleagues reported the recent discovery of most of a skull and associated remains dating to around 300,000 years ago in Hualong Cave (Hualongdong). The features of the Hualongdong fossils complement those of other East Asian remains in indicating a continuity of form through the Middle Pleistocene and into the Late Pleistocene.

In particular, the skull features a low and wide braincase with a projecting brow but a less prominent midface, as well as an incipient chin. The teeth are simple in form, contrasting with other archaic East Asian fossils, and its third molar is either reduced in size or absent.

The virtual reconstruction of the Hualongdong 6 human skull above, with mirror-imaged portions in gray, plus two of the few stone tools from the site. (WU Xiujie)

According to the authors, the remains not only add to the expected variation of these Middle Pleistocene humans, recombining features present in other individuals from the same time period, but also foreshadow developments in modern humans, providing evidence for regional continuity.